What number makes this equation true?
Explanation: ${?}+ 393 = 706$ ${393}$ ${706}$ $+?$ Let's start by adding hundreds to ${393}$ until we get as close to ${706}$ as possible without going over ${706}$. $\begin{aligned} {393} +100}=493\\\\ {493} +100}= 593\\\\ {593} +100}= 693 \end{aligned}$ If we add $3 \text{ hundreds}}$, or $3 00}$, we reach $693$. We cannot add any more hundreds without going over ${706}$. ${393}$ ${706}$ ${693}$ $+300$ Next, let's add tens to $693$ until we get as close to ${706}$ as possible without going over ${706}$. $\begin{aligned} 693 +{10}=703 \end{aligned}$ If we add ${1 \text{ ten}}$, or ${10}$, we reach $703$. We cannot add any more tens without going over ${706}$. ${393}$ ${706}$ ${693}$ ${703}$ $+300$ $+10$ Finally, how many ones should we add to $703$ to get to ${706}?$ $703 +{3}={706}$ ${393}$ ${706}$ ${693}$ ${703}$ $+300$ $+10$ $+3$ We added $3 \text{ hundreds}}$, ${1 \text{ ten}}$, and ${3\text{ ones}}$ to ${393}$ to get to ${706}$. $3 00}+{1 0}+{3}={313}$ ${393}$ ${706}$ ${693}$ ${703}$ $+300$ $+10$ $+3$ $+313$ ${313}+ 393 = 706$